Bias in Judicial Opinion Footnotes?

"The past decade has witnessed an explosion in empirical
articles seeking to rank judges in terms of their relative
performances on the bench. The dominant method of ranking these
judges has been to use citation counts, specifically counts of
citations by other judges. Critics have pointed out that the use
of citation counts for ranking purposes is problematic unless the
citation counts are first tested for the presence of biases,
particularly political bias. Using data on citation practices in
federal circuit court opinions from 1998 to 1999, this Article
seeks to test for the presence of bias in citations. Our findings
suggest bias along three dimensions. First, judges base outside
circuit court citation decisions in part on the political party
of the cited judge. Judges tend to cite judges of the opposite
political party significantly less compared with the fraction of
the total pool of opinions attributable to the opposite political
party judges. Second, judges are more likely to engage in biased
citation practices in certain high stakes situations. These high
stakes situations include opinions dealing with certain subject
matters (such as individual rights and campaign finance) as well
as opinions in which another judge is in active opposition. Third,
judges cite disproportionately more to those judges that cite
back to them frequently, suggesting the presence of citation
clubs."